A bone is an important tissue, which serves as a structural frame to support the body and also supports a mineral control system for body fluid as a reservoir for various minerals such as calcium and phosphorus. In osseous tissue, osteogenesis or bone formation and resorption always remain active to replace old bone by new bone. Especially in a bone the growth of which has finished, osteoblasts in the bone formation system and osteoclasts in the bone resorption system are closely related to each other to repeat bone formation and bone resorption such that the osseous tissue is maintained and minerals in the body fluid are kept constant. This bone reconstitution is called “bone remodeling”. This bone remodeling is precisely controlled by physical factors, hormones, cytokine and the like while maintaining a certain balance. Bone mass, however, decreases if this balance is disturbed and the bone resorption exceeds the bone formation. Of these pathologic decreases in bone mass, one normal in bone components is called “osteoporosis”.
Osteoporosis is known to be one of health troubles from which more people suffer as aging advances, and especially to occur often on postmenopausal females. Osteoporosis tends to result in a fracture of the femoral neck, and like cerebrovascular accident, is a cause of many “bedridden aged persons”, thereby adversely affecting on the society. There is, accordingly, a strong social demand for performing appropriate treatment for osteoporosis to avoid its aggravation and also for establishing an effective method for its prevention. As drugs for osteoporosis, vitamin D preparations, calcitonin preparations, bisphosphonate preparations and the like have been developed and clinically applied to date. It is, however, the current circumstance that these efforts have not led yet to the development of satisfactorily effective drug.
Under the current circumstance that no satisfactory method has been established yet for the treatment of osteoporosis as mentioned above, its prevention is most important. Theoretically, it is possible to keep the bone mass at a high level even when advanced in age, provided that the bone mass can be increased as much as possible in adolescence and maturity, the thus-increased bone mass can be maintained for an extended time and a postmenopausal reduction in bone mass can be suppressed even a little. For this purpose, it is essential to continuously ingest appropriate calcium throughout childhood, adolescence and maturity. Ingestion of calcium alone, however, is not sufficient. If food materials having function to prevent or ameliorate osteoporosis and the like are available, their addition to foods which are taken daily is expected to successfully prevent or ameliorate osteoporosis through the everyday dietary. Further, identification and separation of active ingredients in such food materials are expected to make it possible to use them as preventives or remedies for osteoporosis.
In the meantime, vitamin K which is widely known as a blood coagulation factor was found to also take part in bone metabolism and has been drawing interests, leading to the marketing of a vitamin K2 preparation in Japan as a drug for ameliorating bone mass and pains in osteoporosis. In addition, food materials with vitamin K1 or vitamin K2 contained therein are being increasingly put on the market.
With the foregoing in view, the present invention has as an object thereof the provision of a novel food material useful for the prevention and/or amelioration of a metabolic bone disease, especially osteoporosis. The present invention also has as another object thereof the provision of a pharmaceutical useful for the prevention and treatment of a metabolic bone disease.